bug 1549708: docshell: add nsIDocShell.isForceReloading; r=bzbarsky

Exposes a new nsIDocShell API, isForceReloading, to determine if
the loaded document was force-reloaded or not.

It relies on the underlying behaviour of nsDocShell::IsForceReloading(),
which again relies on nsDocShell::IsForceReloadType(mLoadType).

The getter is used in the remote agent to test that
Page.reload({ignoreCache: true}) works as intended.

Differential Revision: https://phabricator.services.mozilla.com/D51435

--HG--
extra : moz-landing-system : lando

docshell/base/nsDocShell.cpp

@@ -13342,6 +13342,12 @@ nsDocShell::GetColorMatrix(nsTArray<float>& aMatrix) {
 
 #undef MATRIX_LENGTH
 
+NS_IMETHODIMP
+nsDocShell::GetIsForceReloading(bool* aForceReload) {
+  *aForceReload = IsForceReloading();
+  return NS_OK;
+}
+
 bool nsDocShell::IsForceReloading() { return IsForceReloadType(mLoadType); }
 
 NS_IMETHODIMP

docshell/base/nsIDocShell.idl

@@ -1074,6 +1074,12 @@ interface nsIDocShell : nsIDocShellTreeItem
 
   void setColorMatrix(in Array<float> aMatrix);
 
+  /**
+   * Returns true if the current load is a forced reload,
+   * e.g. started by holding shift whilst triggering reload.
+   */
+  readonly attribute bool isForceReloading;
+
   Array<float> getColorMatrix();
 
   /**